The purpose of this proposal is to study the relationship between environmental experiences and the risk of development of multiple myeloma. The principal environmental factors of interest are farming exposure, medical experience, personal life exposure, residential history and occupational exposure. The case-control methodology will be used: 200 cases of confirmed multiple myeloma, ascertained through the community-based cancer detection methods of the Iowa State Health Registry, will be interviewed. These cases will be matched by five-year age strata to 200 controls. One hundred and forty of the controls will be interviewed under the auspices of a concurrent study of leukemia and lymphoma and only 60-70 additional controls will be needed under this proposal. The interview instrument has already been developed under the previously mentioned proposal. The study will be population-based in both case and control selection. Control selection will be by random dialing for controls under age 65 and by selection from social security files for those over the age of 65. Following analysis of the study, a more accurate description of risk factors in the development of multiple myeloma in farming and rural life is anticipated. These data will supplement other current and completed studies by the investigators in the study.